GMR can also be used from the UK to Europe if necessary, including for empty vehicles.
GMRs are compulsory from France and Spain to the UK, even if you are travelling in an empty vehicle.
UCR (DUCR/MUCR) is still allowed. GMR or UCR must be provided.
Temporary storage is also available from France and Spain to the UK if you choose to not use GMR or UCR.
Brittany Ferries